Automatic soldering machine and method



March 26, 1963 c. HEPNER AUTOMATIC SOLDERING MACHINE AND METHOD 4Sheets-Sheet 1 Original Filed Jan. 26, 1956 INVENTOR. W ag pe 2 M 6 WMarch- 26, 1963 c. HEPNER 3,082,520"

AUTOMATIC SOLDERING MACHINE AND METHOD Original Filed Jan. 26, 1956 4Sheets-Sheet 2 II II I I ul nl nllll I ll] III III I ll Mm I March 26,1963 Original Filed Jan. .26, 1956 C. HEPNER AUTOMATIC SOLDERING MACHINEAND METHOD 4 Sheets-Sheet 3 March 26, 1963 c. HEPNER 3,082,520

AUTOMATIC SOLDERING MACHINE AND METHOD Original Filed Jan 26, 1956 4Sheets-Sheet 4 INVENTOR. M' @Qpam 5", M fia/w rates The presentinvention relates to automatic soldering machines, and more particularlyto an improved automatic soldering machine for soldering the contacts ofelectrical and electronic components to corresponding printed circuitpanel assemblies adapted to support and interconnect such components.

This application is a continuation of copending application Serial No.561,427 filed January 26, 1956, now abandoned.

Until recent years most electronic apparatus was mounted on rigid metalchassis, with the contacts of the electrical components therein beingconnected together by wire leads or jumpers. These leads were usuallymanually booked and crimped to the contacts of the components; and theconnections were then soldered, which was also carried out manually.Such a fabricating process is clearly costly, since, among other things,it involves a relatively large number of skilled and semi-skilled manualoperations.

In order to streamline and reduce costs in the manufacturing ofelectronic equipment, printed circuit methods and techniques have comeinto greater and greater prominence in recent years. These circuitsconsist generally of electrical conductors formed on one or bothsurfaces of a thin molded phenolic laminate panel, or other type ofinsulating panel, this being done by any one of a multiplicity ofprinting or plating processes known to the art today. For example, alarge number of successful plated circuit assemblies have been madecommercially by the process described and claimed in Nieter Patent2,699,425 which issued January 11, 1955, and which is assigned to theassignee of the present application.

Printed circuit assemblies, such as those fabricated by the processdescribed in the Nieter patent referred to above, are equipped withinterconnected metallized eyelets extending through the panel and theseeyelets receive the connection of the various electronic componentssupported on the panel. Subsequent soldering of these connections to theeyelets secures the components to the panel, and establishes electricalconnection between the components by means of the conductors imprintedor plated on the surfaces of the panel.

Many expedients have been suggested in the past for providing quick andefiicient soldering of the above mentioned connections into the eyeletsor into equivalent terminals on the printed circuit panel or board. Themost usual of these soldering methods has been the technique knowngenerally as dip soldering. However, dip soldering in general is subjectto several limitations. For example, it is difiicult to provide asimple, mechanical carriage or conveyor for the panels becausestraight-line motion is not compatible with dip soldering. Instead, thepanels must usually be moved successfully in a horizontal direction, andthen individually moved vertically to dip them in to the molten solder.Also there is a problem in dip soldering apparatus of eliminating thescum that forms on the surface of the molten solder in the crucible, andmany elaborate systems have been tried out in an attempt to maintain thesolder surface free from such scum. Another problem is one of heat, thetemperature of the molten solder being sufiiciently high so that damageto the printed circuit panels often results un- "ice less undulyexpensive panels are used having high heat resistance.

It is, accordingly, an object of the present invention to provide animproved automatic soldering machine for the purposes described aboveand in which the above enumerated problems of the prior art aresuccessfully overcome and solved.

A more general object of the invention is to provide an improvedautomatic soldering machine for effecting solder joints on printed orplated circuit panel assemblies.

Another object of the invention is to provide an improved and relativelyinexpensive automatic soldering machine for printed or plated circuitpanel assemblies which is capable of imparting extremely clean, scumfree solder connections to the assembly and at a relatively lowtemperature so that there is no need to use unduly expensive panels forthe printed circuit boards.

Yet another object of the invention is to provide such an improvedsoldering machine for plated or printed circuit panel assembly whichprovides eflicient and essentially continuous soldering to a successionof such assemblies in a simple and rapid manner and with the assem bliesbeing drawn across the solder station along a straight line uniplanarpath.

A feature of the invention is the provision of an automatic solderingmachine which includes a crucible for molten solder, and means (such asa submerged rotating paddle wheel) for producing a hump on the surfaceof the solder in the crucible. The production of such a hump allows thepanels to be drawn in a straight line path over the surface of themolten solder in spaced parallel relation therewith, with each panelpassing across the hump in contact therewith. This expedient not onlyenables the panels to be drawn along a simple uniplanar path, but alsocauses only a small portion of the panel to be contacted by the moltensolder at any one time which reduces heating of the panel to a minimum.

Another feature of the invention is the provision in such a solderingmachine of a rotatable member within the crucible for producing the humpdescribed above, which member is constructed to cause the hump to beformed by pure molten solder drawn from below the surface of the moltensolder mass so that the successive panels may be contacted by purescum-free solder.

The above and other features of the invention which are believed to benew are set forth with particularity in the appended claims. Theinvention itself, however, together with further objects and advantagesthereof, may best be understood by reference to the followingdescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a side view of a machine constructed in accordance with theinvention;

FIG. 2 is a sectional view of the machine taken along the lines 2-2 ofFIG. 1;

FIG. 3 is an end view of the machine taken from the right hand end ofFIG. 1;

FIG. 4 shows a printed circuit panel with various components supportedthereon to be mechanically afiixed to the panel and electricallyconnected to the printed circuit by the soldering operation of themachine of the invention; and

FIG. 5 is a view of the underside of the panel of FIG. 4.

The invention provides an automatic soldering machine which comprises acrucible for housing a quantity of molten solder. A rotatable member isadapted to be submerged in the molten solder in the crucible, and thismember includes a series of angularly spaced axially extending bladesarranged around the axis of rotation of the member and with theirtransverse axes extending essentially radially with respect to such axisof rotation.

drive 29 to the sprocket 25 of speed reducer 23.

- tion.

Upon rotation of this member, the blades create a fiow of molten solderfrom the interior of the member and through the radial spaces betweenthe blades so as to create a hump of molten solder extending across thesurface of the molten solder in the crucible essentially parallel to theaxis of rotation of the member. The height of this hump is a function ofthe rotational speed of the rotatable member, and this height can beconveniently adjusted merely by adjusting such rotational speed. Drivingmeans is provided for imparting rotational motion to the rotatablemember, and the rotational speed of this driving means is convenientlyadjustable for the purposes described above. A suitable guide extendsover the crucible and across the hump in the molten solder therein, andthis guide supports a series of printed circuit panels in spacedparallel relation with the surface of the molten solder in the crucible.Means is then provided for moving the series of printed circuit panelsin succession along the guide means with the undersides of the panelsbeing adapted to be drawn acrgs-s the hump of molten solder and incontact therewit Referring now in particular to FIGS. 1 and 2, theimproved solder machine of the present invention includes a series ofupright supporting members it}, which members are welded or otherwisesecured to a pair of horizontal guides 11 and 12. A pair of sprocketssuch as sprocket 13 are rotatably mounted at one end of the horizontalguides 11 and 12, in spaced coaxial relation. A corresponding pair ofsprockets 14 and 15 are rotatably mounted at the other end of thehorizontal guides 11 and 12 and are also spaced in coaxial relation. Anendless chain 15 is looped over sprockets 13 and 14 and over additionalsprockets 17, '18, 19 and 2%, which latter sprockets are rotatablymounted under the horizontal guides to support the chain on its returnmotion under the upper surface of the bracket 11 and clear it from asolder crucible which will be described. A similar chain 21 (FIGS. 2 and3) is supported by sprocket 15' and other sprockets in respective spacedcoaxial relation with sprockets 17-29 and the previously mentionedsprocket in spaced coaxial relation with sprocket 13. The two chains 16and 21 form a conveyor system, and they are drawn in spaced parallelrelation across the tops of the horizontal guides 11 and 12, and thesechains are returned under these guides and held taut by sprockets 17-20and the above-described additional sprockets which are in respectivecoaxial relation therewith.

The conveyor system comprising the endless chains 16 and 21 is driven bya motor 22 which is supported on a bracket 73 at the right hand end ofthe machine. As best shown in FIG. 3, motor 22 is coupled to aspeed-reducer 23 through a variable drive 24 which is manuallycontrolled by means of a lever 25. A sprocket 26 is driven by the speedreducer and at a reduced speed as compared with the motor. Sprockets 14and 15 are rigidly mounted on a shaft 27, which is rotatably mounted inthe machine on suitable bearings and extends transverse to the directionof motion of chains 16 and 21. A sprocket 28 affixed to shaft 27 iscoupled through a chain In this manner, motor '22 causes the shaft 27 torotate at a reduced speed which, in turn, drives the chains 16 and 21.The variable drive 24 on motor 22 provides a manual control for thespeed of the spaced parallel chains 16 and 21 of the conveyor system.

The spaced parallel chains 16, 21 of the conveyor system pass over thetop of a crucible or pot 30 (FIGS. 1 and 2) which is constructed tocontain molten solder, and the solder pot incorporates suitable heatingelements to maintain the solder therein in a molten condi- A series ofresilient clips '31 (PEG. 2) are fastened to the chains at regularintervals and these clips are adapted to hold a series of printedcircuit assemblies such as the one shown in H6. 4 at spaced positionsalong the chain. As the chains pass over the top of the solder pot 30,the undersides of the successive panel, as shown in FIG. 5, are drawnacross the solder pot in spaced parallel relation with the normal soldersurface in the pot.

As shown particularly in FIG. 2, a rotatable shaft 35 is mounted on apair of brackets 36 and 37 supported by the sides of the crucible, andthis shaft is submerged below the normal level of molten solder in thesolder pot. The shaft 35 is surrounded by a series of axial blades 38which also are submerged below the surface of the solder. The blades 38are positioned respectively around the axis of rotation of the rotatableshaft 35, and each of these blades extends in an axial direction withrespect to the shaft. Moreover, the blades are angularly spaced withrespect to one another and are arranged so that their respectivetransverse axes extend in a radial direction with respect to the shaft.With this arrangment, rotation of shaft 35 causes the blades to create aflow of molten solder from the inner space between them and the shaft,so as to force the solder from this inner space out through the radialspaces between the blades to form a hump extending across the surface ofthe molten solder in the solder pot in a direction essentially parallelto the axis of rotation of shaft 35. This creates a continuous solderflow and because the solder constituting this hump is drawn from belowthe surface of the solder in the solder pot, the hump is constituted bypure scum-free solder. Moreover, the height of the hump can becontrolled merely by controlling the speed of rotation of the blades 38.

The shaft 35- is terminated in an angled gear 39 which engages a matinggear 40, the latter being fixed to a vertical shaft 41. Vertical shaft41 is rotatably mounted in bracket 37 and extends out the top'of thesolder pot. The upper end of the shaft enters a housing 42 supported onone side of crucible 30, and in which housing a suitable transmissionmechanism 43 is mounted which enables the vertical shaft to be driven bythe horizontally mounted sprocket 44. Sprocket 44 is driven through achain drive 45 from a sprocket 46, and the latter sprocket is driven bya motor 47 through a speed reducer 48. The motor 47 is equipped with ausual speed control (not shown) which, in turn, controls the speed ofrotation 35 so that a convenient adjustment for the height of the humpin the solder can be efiectuated.

A pair of parallel guide plates 59 and 51 (FIG. 2) extend into thesolder hump, and these plates are in spaced parallel relation andarranged parallel to the direction of motion of the chains 16 and 21.The guide plates 50 and 51 extend into the molten solder approximatelyto the surface of the rotatable member comprised of blades 38, and thehump of molten solder created by the rotation of these blades causes themolten solder to rise between the guide plates 50 and 51 approximatelyto the respective upper edges of these plates; The horizontal guides 11and 12 are arranged to form a guide means for the respective chains 16and 21 so that these chains are guided over the top of the solder pot insuch a manner that the panels supported thereby are drawn across theupper edges of plates 50 and 51 with their undersides successivelycontacted by the solder hump as it appears between these plates.

As shown in FIG. 4, the printed circuit assembly includes a panel orbase board which has electrical con doctors 61 imprinted thereon by anysuitable process. These conductors terminate in metall-ized eyelet 62which extend through the panel and which receive the various contacts ofthe electronic and electrical components to be supported on the paneland to be electrically interconnected by the printed circuit. As theprinted circuit is drawn across the solder pot, its underside, as shownin FIG. 5, is spaced and parallel tothe surface of the solder in thepot. However, as each panel reaches the upper edges of guides 50 and 51,the underside of each panel is wiped across the humped portion of thesolder surface which forms a solder joint for all the contacts andmetallized terminals 62. As previously noted, a plurality of panels canbe clipped onto the chains 16, 21 in a series to be successively drawnacross the hump for mass-production soldering. As shown in FIG. 1, thepanels may be loaded onto the conveyor system of chains 16, 21 at theleft hand side of the machine, the components can be placed on theindividual panels as they travel towards crucible 38, the assemblies maythen be drawn through appropriate pre-heating and flux-ing stations (notshown) just prior to being drawn over the top of the solder pot 3t), andthey are then drawn in succession across the hump. Then, the completedsoldered assemblies can be unloaded at the right hand side of themachine.

The arrangement is such that straight line continuous motion can be usedsince there is no need to dip the panels down into the solder, instead,the solder is brought up to the undersides of the panels. It has beenfound that satisfactory soldering may be provided with the solder at alower temperature than is required for satisfactory dip soldering.Moreover, since the panel is drawn across the hump, the entireundersurface is not contacted at once, and the heat used is diminished.This permits a cheaper grade of panel to be used. Also, the solder inthe hump is drawn from the interior and is free of scum.

The invention provides, therefore, a simple and improved machine forproviding automatic soldering for printed circuit assemblies, and whichsoldering is more rapid and yet improved as compared with the solderingachieved by prior art machines of this general type.

I claim:

1. A method of applying molten solder to solderable portions of aprinted circuit assembly on a panel of insulating material wherein thesolder contacts such portions in substantially touching contact as theprinted circuit assembly is moved in an assembly line relative to themolten solder, including the steps of rotating mechanical means whollysubmerged in a body of molten solder about a substantially horizontalaxis in a molten solder container, which circulates a volume of moltensolder and causes molten solder to flow from the mechanical circulatingmeans into a controlled moving molten solder hump of a predeterminedheight above the solder in the container that is not a part of the hump,confining the hump to a predetermined width corresponding to the widthof a printed circuit assembly to be soldered by directing the flowingsolder between guide means spaced apart horizontally a distancecorresponding to such predetermined Width, and moving a plurality ofprinted circuit assemblies along a predetermined path positionedrelative to the moving molten solder hump so that the peak portion ofthe solder hump engages an under portion of each assembly insubstantially touching contact.

2. A method of applying molten solder to solderable portions of aprefabricated circuit assembly on a panel of insulating material whereinthe solder contacts substantially the entire width of the panelincluding the solderable portions of the circuit assembly, said methodcomprising providing a body of molten solder in a molten soldercontainer, producing an upward flow of clean molten solder from theinterior of the solder in the container by rotating mechanical meansabout a substantially horizontal axis positioned entirely below thesurface of the solder in the container at a speed of rotation which willraise the flowing solder to a hump formation which extends to apredetermined height above the surface of the solder that is not a partof the hump, confining the hump to a predetermined width correspondingto the width of a prefabricated circuit assembly to be soldered bydirecting the flowing molten solder between confining means whichproject above the normal surface of the solder in the container and arespaced apart horizontally a distance corresponding to such predeterminedwidth, and providing continuous movement of a prefab-i ricated circuitassembly in a predetermined path which traverses the solder hump so thatthe entire underportion of the assembly wipes across the hump of solder.

3. A method of applying molten solder to solderable portions of aprefabricated circuit assembly wherein the solder contacts substantiallythe entire width of the assembly including the solderable portionsthereof, said method comprising providing a body of molten solder in amolten solder container, producing an upward flow of clean molten solderfrom the interior of the solder in the container by rotating mechanicalpumping means positioned entirely below the surface of the solder in thecontainer about a substantially horizontal axis, directing the flow ofmolten solder into a space bounded by confining means situated abovesaid pumping means and spaced horizontally a predetermined distancecorresponding to the width of the circuit assembly and which projectupwardly above the normal surface of the solder in the container,controlling the speed of rotation of said mechanical pumping means sothat the upward flow of molten solder produced thereby forms a raisedhump of flowing molten solder which extends to a predetermined heightabove the surface of the solder that is not a part of the hump and whichis limited by the confining means to a predetermined width correspondingto the width of a prefabricated circuit assembly to be soldered, andproviding continuous movement of a prefabricated circuit assembly in apredetermined path which traverses the solder hump so that the peakportion of the solder hump engages the underportion of the assemblyacross its entire width as the assembly moves across the hump.

4. A soldering machine including in combination, a container having anopening at the top thereof and housing therein a quantity of moltensolder, means for mechanically moving molten solder within the containerin a manner to create a bump of moving molten solder at the opening inthe top thereof and at a height above the surface of said solder in thecontainer so as to accom plish soldering on a workpiece at said opening,said mechanical means including horizontally extending rotatable meanswholly submerged in the solder in said container and having solderraising portions thereon in contact with the molten sold-er in thecontainer, a driving mechanism for rotating said rotatable means andraising the molten solder upwardly to create said hump of molten solderin a position above said rotatable means and to a height such that theupper peak surface of the hump is spaced vertically from the rotatablemeans and extends essentially parallel of the axis of rotation of saidhorizontally extending rotatable means, means having parallel confiningportions spaced apart horizontally and positioned above said rotatablemeans to receive the hump between the same for confining the upper peaksurface of the hump to a width corresponding to the width of the portionto the solder in each workpiece, means for sup porting said workpiece ina manner so that each workpiece is placed at the position of the moltensolder hump with the latter engaging at least an underportion of saidworkpiece, and means for moving a workpiece along said supporting means.

5. A soldering machine including in combination, a container having anopening at the top thereof and housing a body of molten solder,rotatable mechanical means having a horizontal axis of rotation mountedwithin said container in a position wholly submerged beneath an upperlevel of the body of solder and including solder raising portionsthereon in contact with clean scum-free solder in the interior of themolten solder body, means for rotating said rotatable means at apredetermined speed so as to raise a circulating mass of molten solderto a predetermined position above the solder level in the container andat the opening in the container, means having vertical confiningportions spaced above said rotatable means projecting above the normalsurface of the solder in said container, said confining portions beingspaced apart horizontally a predetermined distance corresponding to theWidth of a workpiece to be soldered and efiective to confine the solderin the circulating mass to a hump of said predetermined width which hasa clean scum-free top surface, and means for continuously movingindividual workpieces across the opening and into contact with the cleanscum-free top surfaces of the solder hump.

6. An automatic soldering machine for applying molten solder to anunderportion of printed circuit assemblies and including in combination,a container for housing a quantity of molten solder, a rotatable memberhaving a horizontal axis of rotation entirely submerged below the moltensolder in said container, said rotatable member including a series ofangularly spaced blades arranged around the axis of rotation of saidmember and with transverse axes of such blades extending essentiallyradially With respect tosaid axis of rotation, said blade being adaptedto produce a flow of molten solder through the radial spaces between theblade and thnough the solder above said blades to create a hump ofmolten solder extending across a portion of the surface of molten solderin said container and above the'surface of the remainder of the moltensolder, with the height of said hump being a function of the rotationalspeed of said rotatable member, means having confining portions situatedabove said blades and projecting above the normal surface of the solderin the container and spaced apart horizontally a distance correspondingto the Width of a printed circuit assembly to be soldered for confiningthe hump of solder to such Width, driving means for imparting rotationalmotion to said rotatable member, support means extending over saidcontainer past said hump in the molten solder therein to support aseries of printed circuit panel assemblies in spaced away relation withthe surface of molten solder in said container, and means for moving theseries of printed circuit panels in succession along said support meansso that the under portions only of the assemblies are contacted by thehump of molten solder.

7. An automatic soldering machine for soldering pieces of an assemblytogether including in combination, a crucible for housing a quantity ofmolten solder, a rotatable shaft extending horizontally across saidcrucible beneath the normal molten solder level therein, a drivingmechanism coupled to said shaft for imparting rotational motion thereto,a series of axially extending angularly spaced lades supported on saidshaft around the axis of rotation thereof wholly beneath the solderlevel in said crucible for engaging the molten solder in said crucible,said blades creating continuously moving solder quantity in a humpformation in the molten solder in said crucible upon rotation of saidshaft with said hump extending across said crucible essentially parallelto the axis of rotation of said shaft, a conveyor system extendinghorizontally over said crucible in spaced away parallel relation Withthe surface of the molten solder therein and moving across said hump ina direction essentially at right angles to said axis of rotation tosupport assemblies thereon, a pair of vertical spaced-apart parallelguide plates situated in the crucible above said blades and at rightangles to the direction of movement of the assemblies, said hump beingadapted to :rise to the respective upper edges of said plates, with aplurality of assemblies being adapted to be moved on said conveyorsystem over said respective upper edges of said guide plates, and withthe underportions only of such assemblies being successively contactedby said solder bump.

References Cited in the file of this patent UNITED STATES PATENTS316,896 Hubel et al Apr. 28, 1885 2,387,736 Bierman Oct. 30, 19452,469,392 Jones et al May 10, 1949 2,529,699 Lach Nov. 14, 19502,683,099 Hahn July 6, 1954 2,770,875 Zimmerman Nov. 20, 1956 2,771,050Zimmerman Nov. 20, 1956 2,895,638 Dvorak July 21, 1959 FOREIGN PATENTS712,109 Great Britain July 21, 1954 798,454 Great Britain July 23, 1958

1. A METHOD OF APPLYING MOLTEN SOLDER TO SOLDERABLE PORTIONS OF APRINTED CIRCUIT ASSEMBLY ON A PANEL OF INSULATING MATERIAL WHEREIN THESOLDER CONTACTS SUCH PORTIONS IN SUBSTANTIALLY TOUCHING CONTACT AS THEPRINTED CIRCUIT ASSEMBLY IS MOVED IN AN ASSEMBLY LINE RELATIVE TO THEMOLTEN SOLDER, INCLUDING THE STEPS OF ROTATING MECHANICAL MEANS WHOLLYSUBMERGED IN A BODY OF MOLTEN SOLDER ABOUT A SUBSTANTIALLY HORIZONTALAXIS IN A MOLTEN SOLDER CONTAINER, WHICH CIRCULATES A VOLUME OF MOLTENSOLDER AND CAUSES MOLTEN SOLDER TO FLOW FROM THE MECHANICAL CIRCULATINGMEANS INTO A CONTROLLED MOVING MOLTEN SOLDER HUMP OF A PREDETERMINEDHEIGHT ABOVE THE SOLDER IN THE CONTAINER THAT IS NOT A PART OF THE HUMP,CONFINING THE HUMP TO A PREDETERMINED WIDTH CORRESPONDING TO THE WIDTHOF A PRINTED CIRCUIT ASSEMBLY TO BE SOLDERED BY DIRECTING THE FLOWINGSOLDER BETWEEN GUIDE MEANS SPACED APART HORIZONTALLY A DISTANCECORRESPONDING TO SUCH PREDETERMINED WIDTH, AND MOVING A PLURALITY OFPRINTED CIRCUIT ASSEMBLIES ALONG A PREDETERMINED PATH POSITIONEDRELATIVE TO THE MOVING MOLTEN SOLDER HUMP SO THAT THE PEAK PORTION OFTHE SOLDER HUMP ENGAGES AN UNDER PORTION OF EACH ASSEMBLY INSUBSTANTIALLY TOUCHING CONTACT.
 4. A SOLDERING MACHINE INCLUDING INCOMBINATION, A CONTAINER HAVING AN OPENING AT THE TOP THEREOF ANDHOUSING THEREIN A QUANTITY OF MOLTEN SOLDER, MEANS FOR MECHANICALLYMOVING MOLTEN SOLDER WITHIN THE CONTAINER IN A MANNER TO CREATE A HUMPOF MOVING MOLTEN SOLDER AT THE OPENING IN THE TOP THEREOF AND AT AHEIGHT ABOVE THE SURFACE OF SAID SOLDER IN THE CONTAINER SO AS TOACCOMPLISH SOLDERING ON A WORKPIECE AT SAID OPENING, SAID MECHANICALMEANS INCLUDING HORIZONTALLY EXTENDING ROTATABLE MEANS WHOLLY SUBMERGEDIN THE SOLDER IN SAID CONTAINER AND HAVING SOLDER RAISING PORTIONSTHEREON IN CONTACT WITH THE MOLTEN SOLDER IN THE CONTAINER, A DRIVINGMECHANISM FOR ROTATING SAID ROTATABLE MEANS AND RAISING THE MOLTENSOLDER UPWARDLY TO CREATE SAID HUMP OF MOLTEN SOLDER IN A POSITION ABOVESAID ROTATABLE MEANS AND TO A HEIGHT SUCH THAT THE UPPER PEAK SURFACE OFTHE HUMP IS SPACED VERTICALLY FROM THE ROTATABLE MEANS AND EXTENDSESSENTIALLY PARALLEL OF THE AXIS OF ROTATION OF SAID HORIZONTALLYEXTENDING ROTATABLE MEANS, MEANS HAVING PARALLEL CONFINING PORTIONSSPACED APART HORIZONTALLY AND POSITIONED ABOVE SAID ROTATABLE MEANS TORECEIVE THE HUMP BETWEEN THE SAME FOR CONFINING THE UPPER PEAK SURFACEOF THE HUMP TO A WIDTH CORRESPONDING TO THE WIDTH OF THE PORTION TO THESOLDER IN EACH WORKPIECE, MEANS FOR SUPPORTING SAID WORKPIECE IN AMANNER SO THAT EACH WORKPIECE IS PLACED AT THE POSITION OF THE MOLTENSOLDER HUMP WITH THE LATTER ENGAGING AT LEAST AN UNDERPORTION OF SAIDWORKPIECE, AND MEANS FOR MOVING A WORKPIECE ALONG SAID SUPPORTING MEANS.